Problem: What's the first wrong statement in the proof below that $ \triangle EBC \cong \triangle EBD$ $ \; ?$ $ \overline{BC} $ is parallel to $ \overline{DF} $. This diagram is not drawn to scale. A B C D E F Givens $ \overline{BD} \cong \overline{CF}$ $, \ $ $ \angle DBE \cong \angle CFE$ $, \ $ $ \overline{BE} \cong \overline{EF}$ $, \ $ $ \overline{BE} \cong \overline{AB}$ $, \ $ $ \angle BED \cong \angle BAC$ $, \ $ and $\ $ $ \overline{DE} \cong \overline{AC}$ Proof $ \triangle EFC \cong \triangle EBD$ because SAS $ \overline{CE} \cong \overline{DE}$ because corresponding parts of congruent triangles are congruent $ \triangle ABC \cong \triangle EBC$ because ASA $ \angle BAC \cong \angle BEC$ because corresponding parts of congruent triangles are congruent $ \triangle EBD \cong \triangle ABC$ because SAS $ \triangle EBC \cong \triangle EBD$ because SSS
Solution: Try going through the proof yourself: write down the givens, and then see if they justify the next step for the reason given. Then do the same thing for the next step, and the next, until you run into something that you can't justify, or you finish the proof. $ \triangle EBC \cong \triangle ABC$ is the first wrong statement.